2005 Exam 4

2005 Exam 4 - NAME: _KEY_ EXAM IV BIOLOGY 231 15 December,...

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NAME: _________ KEY _________________ EXAM IV BIOLOGY 231 15 December, 2005 ________________________________________________________________________________ -1- GENERAL INSTRUCTIONS: 1. Answer all questions legibly. 2. Confine each answer to the BOX or SPACE provided. Only what is clearly written in the box or space will be graded! Use the back of the pages for “rough drafts” if you like. 3. SHOW YOUR WORK where appropriate. 4. Make sure that your name is PRINTED LEGIBLY on EACH PAGE. 5. This exam consists of 8 questions on 14 pages and it is worth a total of 100 points. WE WILL NOT OFFER RE-GRADING ON THIS EXAM. If you like, you can pick it up in LILY 2-226 after 12/20/05. 6. Have a happy and safe holiday. Information that may be useful: ! The myosin motor proteins translocate along the surface of actin filaments, toward the plus end. ! The dynein motor proteins translocate along the microtubule surface toward the minus end, the kinesin motor proteins toward the plus end. MT = abbreviation for “microtubule.” ! In the mitotic spindle, chromosomal MTs interact with chromosomes, while polar MTs interact with polar MTs from the opposite half-spindle. Astral microtubules extend toward the cell cortex. ! On this day in 1791, Virginia became the 10 th state to ratify the first 10 amendments to the US Constitution, and the “Bill of Rights” became the law of the land. On this day in 1970, the Venera 7 spacecraft (USSR) became the first earth vehicle to land on another planet (Venus).
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NAME: _________ KEY _________________ EXAM IV BIOLOGY 231 15 December, 2005 ________________________________________________________________________________ -2- (1) (a) 4 pts. You are assembling actin filaments in vitro using purified actin with or without accessory, actin-binding proteins. In each experiment, you allow assembly to proceed to steady state, then you measure the extent of polymerization and also observe the state of the actin filaments by electron microscopy. For each experimental result below, select the ONE CLASS of actin binding protein that is most likely to give the result, and WRITE IT in the box to the right of the experiment. The first row is a control and requires no answer. start with: progress of polymerization: appearance in EM class of accessory protein added? 2 uM pure actin 2' lag phase, then steady polymerization until 90% of actin is in filaments average length = 5 um NONE 2 uM pure actin plus accessory protein 1 2' lag phase, then steady polymerization until 85% of actin is in filaments average length = 2 um severing 2 uM pure actin plus accessory protein 2 no lag phase, steady polymerization until 90% of actin is in filaments average length = 5 um nucleating 2 uM pure actin plus accessory protein 3 2' lag phase, then steady polymerization until 60% of actin is in filaments average length = 5 um monomer-seq 2 uM pure actin plus accessory protein 4 2' lag phase, then steady polymerization until 90% of actin is in filaments average length =
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2005 Exam 4 - NAME: _KEY_ EXAM IV BIOLOGY 231 15 December,...

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